Dipper tooth for excavating shovel with key means free of shearing and bending stress



July 8, 1969 F. E. TRUDEAU DIPPER TOOTH FOR EXCAVATING SHOVEL WITH KEY MEANS FREE OF SHEARING AND BENDING STRESS Filed June 5, 1967 INVENTOR y 8, 1969 F. E. TRUDEAU 3,453,755

DIPPER TOOTH FOR EXUAVATING SHOVEL WITH KEY MEANS FREE OF SHEARING AND SENDING STRESS Filed June 1967 Sheet 2 of 2 INVENT OR FRANCIS E. TRUDEAU ATTORNEY United States Patent DIPPER TOOTH FOR EXCAVATING SHOVEL WITH KEY MEANS FREE OF SHEARING AND BEND- ING STRESS Francis E. Trudeau, Chicago, Heights, 111., assignor to Portec, Inc., Chicago, L, a corporation of Delaware Filed June 5, 1967, Ser. No. 643,563 Int. Cl. E02f 9/28 U.S. Cl. 37-142 4 Claims ABSTRACT OF THE DISCLOSURE A two-part dipper tooth for excavating shovels wherein a wedge-shaped key is frictionally engaged in related registering openings in the point of the tooth and in spaced pockets in the bifurcated nose of the base. Opposed surfaces of the key are in engagement with tapered shoulders formed in the pockets and with the vertical wall of an opening in the point to place the key in compression over a large bearing area and eliminate bending and shearing stresses.

This invention relates generally to replaceable dipper teeth for excavating shovels and particularly to the shape of the key and its relation to and cooperation with bearing surfaces in an opening in the tooth point and related tapered pockets in the nose of the base portion of the tooth.

It is well known in the prior art to provide replaceable dipper teeth wherein a tapered key member is employed to connect a replaceable point with the base. In such prior art devices, when the base, point, and key are assembled, the key normally bears against surfaces of the base and point at its ends on one side, and at its center on the opposite side. An example of this type of arrangement is shown in U.S. Patent No. 943,775. When the key is so positioned, it has a tendency to bow or bend into an arcuate shape because of the exertion of highly concentrated pressure at relatively small bearing areas. These small overstressed bearing areas have a tendency to compress and permit the key to work loose. Furthermore, the key is in shear at two places where it is confined in the related and registering openings in the point and base.

The primary object of this invention is to overcome these deficiencies of the prior art by providing continuous bearing surfaces on the front and rear faces of a wedgeshaped key when the key is assembled in friction-tight engagement with the point and base, which arrangement eliminates the tendency of the key to bend and also eliminates shear stresses otherwise encountered.

Another object of the invention is to provide a retainer key having angular side surfaces so that when it is fitted into an opening or openings of similar cross section, it will resist twisting due to external forces.

A further object of the present invention is to eliminate separate retainer means commonly employed with keys of the type known in the prior art, which retainer means frequently comprises bolts, pins, or, in some cases, a forked end portion which is spread apart to lock the key in place. A key tightly driven into position in the cooperating openings in the point and base according to the present invention, is entirely in compression over a large bearing area and there is no action resulting from the normal operation and function of a dipper tooth which causes the key to become loose and work itself out of position.

With the above and other objects in view which will become more readily apparent as the nature of the invention is better understood, the same consists in the novel construction, combination and arrangements of parts as hereinafter more fully described, illustrated, and claimed.

Referring to the drawings:

FIGURE 1 is an exploded perspective view of the base point and key of the present invention prior to assembly.

FIGURE 2 is a side elevation of the base point and key in assembled relation with a protruding portion of the key shown in dotted lines.

FIGURE 3 is a view similar to FIGURE 2, showing the tooth in section along the line 3-3 of FIGURE 4, parts of the base also being shown in section.

FIGURE 4 is a top plan of the point.

FIGURE 5 is a top plan of the base.

Similar reference characters designate corresponding parts throughout the several figures of the drawings.

Referring to the drawings in detail, particularly FIG- URE 1, it will be seen that the base, generally referred to as 1, includes a central body portion 2, a rearwardly extending attaching shank 3, and a forwardly extending wedge-shaped bifurcated nose 4. The nose 4 is provided with a slot 5 to form a pair of arms 6 and 7. The arms 6, 7 are each provided on their inner opposed faces 11, 12, respectively, with pockets 13, 13' which include inclined or tapered shoulders 14, 15 formed in the front portion of each pocket, that is, the portion closest to the tips of the arms 6 and 7 and facing rearwardly towards central body portion 2. The shoulders provide a sloping bearing surface for the tapered side of a wedge-shaped key 16 of generally rectangular cross section, as will be later described in detail.

The point 17 is also of wedge shape with symmetrical upper and lower walls 18, 19, respectively, complementary to the tapered surfaces of the arms 6, 7 of nose 4 of the base. The point is provided with a pair of spaced sockets 20, 21 opening at the rear wall 22 and separated by a vertical web 23. These sockets are adapted to receive arms 6, 7 when the base is assembled with the point.

Inwardly of the rear wall 22 of the point 17, a key receiving opening 24 extends through the upper wall 18, through web 23 and the lower wall 19. This opening is of substantially larger diameter than the width of web 23; consequently, the web is completely cut away to provide a communicating opening 26 between sockets 20 and 21. The opening 24 thus has continuous front and rear walls 25, 25', respectively, extending throughout the height thereof but discontinuous side walls due to communicating opening 26. The opening 24 is also of greater diameter than the largest diameter of wedge-shaped key 16 so that when the key is assembled with the point and base, as will later be described, the inclined shoulders 14, 15 on the nose of the base grip the related surface of the key and thus provide one of the two opposed supporting surfaces for the key.

The key 16 has a vertical rear face 27, a front face 28, and parallel side faces 29, 30 which are bevelled at 31, 32 to clear the corner radii in openings 24, 25 and pockets 13, 13. The front face 28 tapers or converges toward the bottom 33 of the key as shown in FIGURES 1 and 3, to provide, together with the rear face, a wedge-shaped key. Although the key shown in the drawings is of generally rectangular shape in cross section, it is understood that this is exemplary only. Thekey could be of other angular cross sectional shapes, provided there are continuous, opposed bearing surfaces front and rear for engagement with the related surfaces of the web 23 and inclined shoulders 14, 15 of the pockets to place the key in compression rather than shear position when it is installed in locking position with the base and point.

When the point 17 is assembled on the base 1 as shown in FIGURE 3, with the arms 6, 7 engaged in the related sockets 20, 21, the pockets 13, 13 in the arms 6, 7 extend partially into the opening 26 such that the shoulders 14, 15 of the sockets provide, in combination with the rear wall 25 of opening 24, bearing surfaces for the rear and front faces of the key 16. As the key 16 is inserted in opening 24 and driven downwardly, its front tapered face 28 engages the inclined shoulders 14, 15 of the pockets 13, 13, and its opposite rear face 27 engages the related vertical rear wall 25' of opening 24. The side faces 29, 30 of the key do not engage related surfaces in the walls of opening 24, since said opening is of greater diameter than the key. The key is thus tightly wedged in position front to rear and is in compression only, thereby eliminating bending and shear stresses. It will be noted from FIGURE 3 that the entire length of the rear face 27 of the key which is within the opening 24 abuts the wall 25' to provide full bearing on the surface of the key, while a large, directly opposite bearing surface is provided by shoulders 14, 15 on the front face 28 of the key.

The key 16 would normally be manufactured so as to be of a length greater than the widest vertical dimension of the average point, as shown in FIGURES 1-3, to allow for variation in fitting the key to different types of points and to permit take-up in case the fit of the base and point becomes worn. Any excess length of the key protruding beyond the surface of the point can be burned off with an acetylene torch. The take-up just referred to is achieved in the following manner:

The relationship of the shape of the arms 6, 7 to the sockets 20, 21 is such that when initial assembly of the parts is made, the tips of the arms are spaced from the base of the sockets as shown in FIGURE 3. As wear occurs between related bearing surfaces of the arms and sockets after extensive use, the key 16 may be driven in and, due to the relationship of the key and the opposed vertical bearing surfaces of opening 24 and inclined surfaces of shoulders 14, 15, the point will be drawn towards the base to restore its original snug fit. As will be seen from FIGURE 3, there is adequate space between the front surface 28 of the key 16 and the wall 25 of opening 24 to permit take-up as described.

I claim:

1. A two-part dipper tooth for excavating shovels comprising a base, a point, and a wedge-shaped key, a bifurcated tapered nose extending from one end of said base, said point including top, bottom and rear walls and a pair of spaced, parallel, tapered sockets open at the rear wall for receiving said bifurcated nose when said base and point are assembled, a web between said sockets, said point having a key receiving opening extending through the top and bottom walls thereof and through said web, the opening through said web communicating laterally with said sockets, key engaging means on said nose to provide a bearing surface for one side of said key, key engaging means on said point directly opposite said key engaging means on said nose to provide a hearing surface for an opposite side of said key, whereby when said base and point are assembled with said key frictionally secured in said opening, said key is placed in compression over a large bearing area between said nose and point key engaging means without creating bending or shearing stresses in said key.

2. A dipper tooth according to claim 1, wherein the key engaging means on said bifurcated nose comprises spaced shoulders inclined toward the key engaging means on said point when said point and base are assembled.

3. A dipper tooth according to claim 2, wherein the key engaging means on said point comprises the vertical rear wall of said opening.

4. A dipper tooth according to claim 3, wherein said key is provided with flat front and rear faces, the front face being inclined relative to the rear face.

References Cited UNITED STATES PATENTS 2,108,075 2/ 1938 Mork 37-142 2,159,104 5/1939 Ratkowski 37142 2,311,463 2/1943 Page 37142 2,891,333 6/1959 Van Buskirk 37-142 2,934,842 5/1960 Van Buskirk 37-142 3,079,710 3/1963 Larsen et a1. 37-142 EDGAR S. BURR, Primary Examiner. 

